JP4573231B2 - Blood purification equipment - Google Patents

Description

  The present invention relates to a blood purification apparatus for purifying a patient's blood while circulating it outside the body.

  In general, in blood purification therapy such as dialysis treatment, a blood circuit composed of a flexible tube is used to circulate a patient's blood extracorporeally. This blood circuit is mainly composed of an arterial blood circuit in which an arterial puncture needle for collecting blood from a patient is attached to the tip, and a venous blood circuit in which a venous puncture needle for returning blood to the patient is attached to the tip. The dialyzer is interposed between the arterial blood circuit and the venous blood circuit to purify blood circulating outside the body.

  In such a dialyzer, a plurality of hollow fibers are arranged inside, and blood passes through the inside of each hollow fiber, and on the outside thereof (between the outer peripheral surface of the hollow fiber and the inner peripheral surface of the housing). It is set as the structure which can flow a dialysate. The hollow fiber has a blood purification membrane with micropores (pores) formed in the wall surface, and waste products of blood passing through the hollow fiber permeate the blood purification membrane and are discharged into the dialysate. At the same time, waste blood is discharged and purified blood returns to the patient's body. In the dialysis machine, a water removal pump for removing water from the patient's blood is disposed, and water removal is performed during dialysis treatment.

  By the way, for example, when an arterial puncture needle and a venous puncture needle are punctured around a patient's shunt (a site where an artery and a vein are connected by surgery) and the periphery thereof to perform extracorporeal circulation, purification is performed from the venous puncture needle. In some cases, blood recirculation occurs in which the blood that has been returned to the patient's body is reintroduced from the arterial puncture needle without passing through the patient's organ or the like. When such blood recirculation occurs, the purified blood is further circulated extracorporeally, and the amount of extracorporeal blood that needs to be purified decreases accordingly, resulting in a problem that blood purification efficiency deteriorates. End up.

  However, conventionally, a dialysis apparatus has been proposed that can detect blood recirculation by using a dehydration pump that is driven rapidly and only for a short period of time to give a unique peak to changes in the concentration of blood circulating outside the body. (For example, refer to Patent Document 1). According to the dialysis apparatus disclosed in this document, a sensor for detecting blood concentration (a sensor for detecting hemoglobin concentration) is disposed in the arterial blood circuit, and by detecting a specific peak with such a sensor, Blood recirculation during dialysis treatment can be detected.

Furthermore, conventionally, in addition to the sensor disposed in the arterial blood circuit, a similar sensor is also provided in the venous blood circuit to confirm whether or not a specific peak has been given to the change in blood concentration. In addition, there has been proposed a technique that can reliably and accurately detect blood recirculation by reducing the parameters for obtaining the ratio of recirculated blood (see, for example, Patent Document 2).
Special Table 2000-502940 JP 2006-087907 A

  However, since the conventional blood purification apparatus simply detects blood recirculation, there is a problem that it is still difficult to perform blood purification treatment considering the blood recirculation. That is, even if blood recirculation is detected, for example, there is any influence on the circulating blood volume change rate (ΔBV), which is an index indicating the patient's condition, and the clearance value, which is an index indicating the amount and efficiency of dialysis by the dialyzer. It is difficult for a medical staff such as a doctor to predict in real time, and an ideal blood purification treatment in consideration of the blood recirculation cannot be performed.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a blood purification apparatus capable of performing an ideal blood purification treatment in consideration of blood recirculation.

  The invention according to claim 1 is a blood circuit including an arterial blood circuit and a venous blood circuit for circulating the collected patient's blood extracorporeally, a blood pump disposed in the arterial blood circuit, and the arterial side. A blood purification means for purifying blood flowing between the blood circuit and the venous blood circuit, and a concentration measuring means for measuring a blood index indicating the concentration of blood circulating outside the blood circuit And the recirculation rate indicating the ratio of the flow rate of recirculated blood that is returned to the patient from the venous blood circuit to the arterial blood circuit with respect to the blood flowing through the arterial blood circuit. A blood purification apparatus comprising a recirculation rate deriving unit, comprising a true value deriving unit for obtaining a true blood index in the patient based on the recirculation rate obtained by the recirculation rate deriving unit. And butterflies.

  The invention according to claim 2 is the blood purification apparatus according to claim 1, wherein the concentration measuring means comprises a hematocrit sensor that is disposed in the blood circuit and measures a hematocrit value of blood flowing through the blood circuit. The true blood index to be obtained by the true value deriving means is a hematocrit value.

  According to a third aspect of the present invention, in the blood purification apparatus according to the second aspect, the circulating blood volume change rate, which is an index indicating the patient's condition, is calculated based on the true hematocrit value obtained by the true value deriving means. It is characterized by that.

  According to a fourth aspect of the present invention, in the blood purification apparatus according to any one of the first to third aspects, the concentration measuring means is provided in each of the arterial blood circuit and the venous blood circuit in the blood circuit. It is arranged.

  According to a fifth aspect of the present invention, in the blood purification apparatus according to the first aspect, the blood purification means comprises a dialyzer for introducing or deriving dialysate through a dialysis membrane, and the concentration measuring means is derived from the dialyzer. The blood index indicating the blood concentration can be measured from the dialysate pressure which is the pressure of the dialysate.

  According to a sixth aspect of the present invention, in the blood purification apparatus according to the first aspect, the concentration measuring means is disposed in the blood circuit and measures a hematocrit value of blood flowing through the blood circuit, and the blood A solute concentration measuring sensor for measuring a solute concentration of blood flowing through the circuit is used, and a true blood index to be obtained by the true value deriving means is a solute concentration.

  According to a seventh aspect of the present invention, in the blood purification apparatus according to the sixth aspect, the blood purification means comprises a dialyzer for introducing or deriving dialysate through a dialysis membrane and is obtained by the true value deriving means. Based on the true solute concentration, a clearance value that is an index indicating the amount and efficiency of dialysis by the dialyzer is calculated.

  According to the invention of claim 1, since the true blood index in the patient can be obtained by the true value deriving means based on the recirculation rate obtained by the recirculation rate deriving means, the blood recirculation is taken into consideration. Ideal blood purification treatment can be performed.

  According to the invention of claim 2, since the true blood index to be obtained by the true value deriving means is the hematocrit value, the hematocrit value and various indices obtained from the hematocrit value can be obtained with high accuracy.

  According to the invention of claim 3, since the circulating blood volume change rate, which is an index indicating the patient's condition, is calculated based on the true hematocrit value obtained by the true value deriving means, the accurate circulating blood volume changing rate is calculated. Can be obtained in real time, and if used as an index during blood purification treatment, ideal blood purification treatment considering blood recirculation can be performed.

  According to the invention of claim 4, since the concentration measuring means is disposed in each of the arterial blood circuit and the venous blood circuit in the blood circuit, it is provided only in either the arterial blood circuit or the venous blood circuit. Compared to a device equipped with concentration measuring means, the parameters for determining the ratio of recirculated blood (recirculation rate) can be reduced, and the recirculation rate can be determined reliably and accurately, and more quickly. A true blood index can be determined.

  According to the invention of claim 5, since the concentration measuring means can measure the blood index indicating the blood concentration from the dialysate pressure that is the pressure of the dialysate derived from the dialyzer, the concentration measuring means is placed on the blood circuit side. It is not necessary to have it.

  According to the sixth aspect of the present invention, since the true blood index to be obtained by the true value deriving means is the solute concentration, it is possible to accurately obtain the solute concentration and various indices obtained from the solute concentration.

  According to the invention of claim 7, since the clearance value, which is an index indicating the amount and efficiency of dialysis by the dialyzer, is calculated based on the true solute concentration obtained by the true value deriving means, the clearance value is accurately obtained in real time. If it is used as an index during blood purification treatment, ideal blood purification treatment considering blood recirculation can be performed.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
The blood purification apparatus according to the first embodiment is for purifying a patient's blood while circulating it extracorporeally, and is applied to a dialysis apparatus used in dialysis treatment. As shown in FIG. 1, such a dialysis machine is mainly composed of a blood circuit 1 to which a dialyzer 2 as blood purification means is connected, and a dialysis machine body 6 for removing water while supplying dialysate to the dialyzer 2. . As shown in the figure, the blood circuit 1 is mainly composed of an arterial blood circuit 1a and a venous blood circuit 1b made of a flexible tube. The arterial blood circuit 1a and the venous blood circuit 1b A dialyzer 2 is connected between them.

  An arterial puncture needle a is connected to the tip of the arterial blood circuit 1a, and an iron-type blood pump 3 and a first hematocrit sensor 5a (concentration measuring means) are disposed on the way. On the other hand, a venous puncture needle b is connected to the distal end of the venous blood circuit 1b, and a second hematocrit sensor 5b (concentration measuring means) and a drip chamber 4 for removing bubbles are connected to the venous blood circuit 1b. .

  That is, the first hematocrit sensor 5a and the second hematocrit sensor 5b constituting the concentration measuring means in the present embodiment are disposed in the arterial blood circuit 1a and the venous blood circuit 1b, respectively. A blood index (specifically, hematocrit value) indicating the concentration of circulating blood can be measured in real time. Here, the hematocrit value is an index indicating the concentration of blood, and is specifically expressed by the volume ratio of erythrocytes in whole blood.

  When the blood pump 3 is driven while the patient is punctured with the arterial puncture needle a and the venous side puncture needle b, the blood of the patient reaches the dialyzer 2 through the arterial blood circuit 1a. As a result, blood purification is performed, and defoaming is performed in the drip chamber 4 to return to the patient's body through the venous blood circuit 1b. That is, the blood of the patient is purified by the dialyzer 2 while circulating outside the body by the blood circuit 1.

  The dialyzer 2 is formed with a blood introduction port 2a, a blood outlet port 2b, a dialysate inlet port 2c, and a dialysate outlet port 2d in the casing. Among these, the blood inlet port 2a has an arterial blood circuit 1a. The base end of the venous blood circuit 1b is connected to the blood outlet port 2b. The dialysate introduction port 2c and the dialysate lead-out port 2d are connected to a dialysate introduction line L1 and a dialysate discharge line L2 extending from the dialyzer body 6, respectively.

  A plurality of hollow fibers are accommodated in the dialyzer 2, the inside of the hollow fibers is used as a blood flow path, and the flow of dialysate is between the hollow fiber outer peripheral surface and the inner peripheral surface of the housing. It is considered a road. A hollow fiber membrane is formed in the hollow fiber by forming a large number of minute holes (pores) penetrating the outer circumferential surface and the inner circumferential surface, and impurities in the blood are passed through the membrane in the dialysate. It is comprised so that it can permeate | transmit.

  On the other hand, as shown in FIG. 2, the dialysis machine main body 6 bypasses the dual pump P formed across the dialysate introduction line L1 and the dialysate discharge line L2 and the dual pump P in the dialysate discharge line L2. It is mainly composed of a connected bypass line L3 and a water removal pump 8 connected to the bypass line L3. One end of the dialysate introduction line L1 is connected to the dialyzer 2 (dialyte introduction port 2c), and the other end is connected to a dialysate supply device 7 for preparing a dialysate having a predetermined concentration.

In addition, one end of the dialysate discharge line L2 is connected to the dialyzer 2 (dialysate outlet port 2d) and the other end is connected to a drainage means (not shown). After the liquid reaches the dialyzer 2 through the dialysate introduction line L1, it is sent to the drainage means through the dialysate discharge line L2 and the bypass line L3. In the figure, reference numerals 9 and 10 denote a heater and a deaeration means connected to the dialysate introduction line L1.

  The dewatering pump 8 is for removing water from the blood of the patient flowing through the dialyzer 2. That is, when the dewatering pump 8 is driven, since the duplex pump P is a fixed type, the volume of liquid discharged from the dialysate discharge line L2 is larger than the amount of dialysate introduced from the dialysate introduction line L1. Thus, water is removed from the blood by the large volume. In addition, you may make it remove a water | moisture content from a patient's blood by means other than this water removal pump 8 (for example, what utilizes what is called a balancing chamber etc.).

  However, the water removal pump 8 of the present embodiment can perform water removal rapidly and in a short time in addition to water removal necessary for dialysis treatment. That is, water removal at a constant rate performed during dialysis treatment is temporarily stopped (however, extracorporeal circulation is performed), and when the measured hematocrit value is stabilized, the water removal pump 8 is driven rapidly and for a short time. By performing water removal, it is configured so that a peculiar peak can be given to a change in blood concentration (hematocrit value) during that time. Here, the term “abrupt and short time” in the present invention means a size and time enough to confirm the pulse applied after passing through the circuit, and “specific” means fluctuations in the pump and the patient's body. It can be distinguished from fluctuation patterns due to other factors caused by movement.

  More specifically, as shown in FIG. 3, at a time t1, water removal at a constant rate (normal water removal) is stopped, and thereafter, when the measured hematocrit value reaches a stable time t2. The water pump 8 is driven at a higher speed than usual until time t3. The time t2 to t3 is a minute time. Thereby, compared with normal water removal, water removal can be performed rapidly and in a short time, and for example, a specific peak can be given in the hematocrit value as shown in FIG.

  As described above, the first hematocrit sensor 5a and the second hematocrit sensor 5b are disposed in the arterial blood circuit 1a and the venous blood circuit 1b, respectively, and the concentration of blood flowing through these circuits (specifically, hematocrit) For example, a light-emitting element such as an LED and a light-receiving element such as a photodiode. The light is emitted from the light-emitting element to the blood, and the transmitted or reflected light is received by the light-receiving element. By doing so, a hematocrit value indicating the blood concentration of the patient is detected.

  Specifically, a hematocrit value indicating the blood concentration is obtained based on the electrical signal output from the light receiving element. That is, each component of blood such as red blood cells and plasma has its own light absorption characteristics, and this property is used to quantify the red blood cells necessary for measuring the hematocrit value electro-optically. Thus, the hematocrit value can be obtained. More specifically, near infrared rays irradiated from the light emitting element are incident on blood, are affected by absorption and confusion, and are received by the light receiving element. The light absorption / scattering rate is analyzed from the intensity of the received light, and the hematocrit value is calculated.

  Since the first hematocrit sensor 5a configured as described above is disposed in the arterial blood circuit 1a, it detects the hematocrit value of blood collected from the patient via the arterial puncture needle a during dialysis treatment. Since the second hematocrit sensor 5b is disposed in the venous blood circuit 1b, it detects the hematocrit value of the blood purified by the dialyzer 2 and returned to the patient. That is, the specific peak given by the water removal pump 8 is first detected by the second hematocrit sensor 5b (see FIG. 4), and then the blood reaches the arterial blood circuit 1a again and is recirculated. The first hematocrit sensor 5a can detect the characteristic peak remaining in the recirculated blood (see FIG. 5).

  Therefore, it can be confirmed whether or not a specific peak has been given by the water removal pump 8 by the second hematocrit sensor 5b, and the presence or absence of recirculated blood can be detected by the first hematocrit sensor 5a. That is, since it is possible to confirm whether or not a specific peak has been given by the water removal pump 8, detection of blood recirculation can be detected more reliably and accurately than in the case where the hematocrit sensor is provided only in the arterial blood circuit 1a. Can be done.

  Further, as shown in FIG. 6, the first hematocrit sensor 5a and the second hematocrit sensor 5b are electrically connected to a calculation means 11 disposed in the dialysis apparatus body 6, and the calculation means 11 includes: A true value deriving unit 12 and a circulating blood volume change rate calculating unit 13 are electrically connected to a display unit 14 such as a liquid crystal screen. The computing means 11 is constituted by, for example, a microcomputer, and compares the hematocrit values (specific peaks) detected by the first hematocrit sensor 5a and the second hematocrit sensor 5b, and blood flowing through the arterial blood circuit 1a. Of the recirculated blood in the blood (that is, the blood flow returned to the patient from the venous blood circuit 1b is led to the arterial blood circuit 1a again and flows to the blood flowing through the arterial blood circuit 1a. It is a ratio and can be calculated hereinafter.

  Specifically, when there is blood recirculation, the time from when a specific peak is given by the water removal pump 8 until the blood reaches the second hematocrit sensor 5b (time t5 in FIG. 4) and recirculation. Then, the time to reach the first hematocrit sensor 5a (t7 in FIG. 5) is predicted, and is detected by the second hematocrit sensor 5b when the time t5 has elapsed after the application of a specific peak by the water removal pump 8. The computing means 11 compares the hematocrit value with the hematocrit value detected by the first hematocrit sensor 5a when the time t7 has elapsed.

  Thus, by predicting the time t5 until the blood reaches the second hematocrit sensor 5b and the time t7 until the blood reaches the first hematocrit sensor 5a by recirculation, the cardiopulmonary recirculation (the purified blood becomes the heart). Or a phenomenon of being pulled out of the body without passing through other tissues or organs) and recirculation to be measured. Instead of such a method, the calculation means 11 recognizes that the hematocrit value detected by the first hematocrit sensor 5a and the second hematocrit sensor 5b exceeds a predetermined value, and the hematocrit values exceeding the value are May be compared.

  Then, based on the time-hematocrit value graphs as shown in FIGS. 4 and 5, the change in the hematocrit value of the first hematocrit sensor 5a and the second hematocrit sensor 5b is obtained, and the time portion to be compared as described above ( The area of the change part is calculated by a mathematical method such as an integration method. For example, the area of the change portion (portion from t5 to t6 in FIG. 4) by the second hematocrit sensor 5b is Sv, and the area of the change portion (portion from t7 to t8 in FIG. 5) by the first hematocrit sensor 5a is Sa. In other words, the recirculation rate AR is obtained by the following arithmetic expression.

  AR (%) = Sa / Sv × 100

  Here, the time of the change portion (time interval from t7 to t8) by the first hematocrit sensor 5a is diffused in the process in which blood with a specific peak flows from the second hematocrit sensor 5b to the first hematocrit sensor 5a. In view of this, it is set to be larger than the time of the change portion (time interval from t5 to t6) by the second hematocrit sensor 5b.

  Thus, the water removal pump 8 and the calculation means 11 that can give a specific peak constitute the recirculation rate deriving means in the present embodiment, and the recirculation rate can be obtained thereby. The recirculation rate obtained by the computing means 11 is sent to a true value deriving means 12 constituted by a microcomputer or the like, for example, so that a true hematocrit value (blood index) in the patient is obtained.

  That is, the first hematocrit sensor 5a measures the hematocrit value of blood that has not been purified by the dialyzer 2. Therefore, if there is no blood recirculation, the value measured by the first hematocrit sensor 5a should be the patient's hematocrit value. However, if there is blood recirculation, the true hematocrit value is calculated by the true value deriving means 12 in consideration that the measurement value by the first hematocrit sensor 5a does not necessarily match the true hematocrit value of the patient due to the influence. It is configured to be obtained.

  Specifically, as shown in FIG. 7, the flow rate (shunt flow rate) of the shunt (human body side blood vessel short-circuit portion or the like) is Qa, and the flow rate of blood flowing through the blood circuit 1 by the action of the blood pump 3 (blood pump flow rate) ) Is Qb, the recirculated blood flow rate (recirculation flow rate) is Qr, the hematocrit value measured by the first hematocrit sensor 5a is Ht1, the hematocrit value measured by the second hematocrit sensor 5b is Ht2, and the purification is performed. When the hematocrit value (true hematocrit value) of the shunt before processing is Hta, these are expressed by the following relational expression.

Ht1 * Qb = Hta * Qa + Ht2 * Qr (Formula 1)
(However, Qa ≦ Qb, Qb = Qa + Qr)

Here, since Qb = Qa + Qr, it can be expressed as Qa = Qb−Qr, and when the recirculation rate is AR, the recirculation rate (AR) = Qr / Qb, so that Qr = AR × Qb can be expressed, and when these are substituted into the above equation 1, the following equation is obtained.
Ht1 * Qb = Hta * Qb * (1-AR) + Ht2 * Qb * AR (Formula 2)

From the above formula 2, the formula for obtaining the true hematocrit value Hta is as follows.
Hta = (Ht1−Ht2 × AR) / (1−AR) (Formula 3)
That is, Ht1 that is the measured value of the first hematocrit sensor 5a, Ht2 that is the measured value of the second hematocrit sensor 5b, and AR obtained by the computing means 11 are known parameters. The hematocrit value Hta can be obtained.

  According to this embodiment, the true blood index (hematocrit value) in the patient can be obtained by the true value deriving means 12 based on the recirculation rate obtained by the computing means 11 (recirculation rate deriving means). Therefore, an ideal blood purification treatment considering blood recirculation can be performed. Further, since the true blood index to be obtained by the true value deriving means 12 is a hematocrit value, the hematocrit value and various indices obtained from the hematocrit value can be obtained with high accuracy.

  Furthermore, the true hematocrit value obtained as described above is sent to the circulating blood volume change rate calculation means 13 constituted by, for example, a microcomputer, and is an index indicating the patient's condition based on the true hematocrit value. The circulating blood volume change rate (ΔBV) can be calculated. This rate of change in circulating blood volume (ΔBV) is (hematocrit value at the start of dialysis (Ht (0)) − hematocrit value at the time of measurement (Ht (t))) / hematocrit value at the time of measurement (Ht (t)) × Since it can be obtained by an arithmetic expression of 100, the circulating blood volume change rate (ΔBV) can be calculated by substituting the true hematocrit values (Ht (0) and Ht (t)) into such an expression.

  Therefore, according to the present embodiment, the circulating blood volume change rate calculation unit 13 calculates the circulating blood volume change rate (ΔBV) based on the true hematocrit value obtained by the true value deriving unit 12, so that the accuracy can be improved. A good circulatory blood volume change rate (ΔBV) can be obtained in real time, and if used as an index during blood purification treatment, ideal blood purification treatment considering blood recirculation can be performed. The circulating blood volume change rate (ΔBV) calculated by the circulating blood volume change rate calculating means 13 is displayed on the display means 14 in real time.

  Further, according to the present embodiment, the first hematocrit sensor 5a and the second hematocrit sensor 5b as concentration measuring means are disposed in the arterial blood circuit 1a and the venous blood circuit 1b in the blood circuit 1, respectively. Therefore, as compared with the case where only one of the arterial blood circuit 1a and the venous blood circuit 1b is provided with a hematocrit sensor as a concentration measuring means, the parameter for determining the recirculation rate is reduced and the recirculation rate is reduced. Reliable and accurate circulation rate can be determined, and true blood index can be determined more quickly

However, in the present embodiment, as described above, the first hematocrit sensor 5a and the second hematocrit sensor 5b as the concentration measuring means are disposed in each of the arterial blood circuit 1a and the venous blood circuit 1b. Instead of this, it may be provided only in the arterial blood circuit 1b. In this case, if the water removal amount Quf (known parameter) by the water removal pump 8 is used, the true hematocrit value Hta can be obtained by the following equation.
Hta = {Ht1- (Ht1 * AR * Qb) / (Qb-Quf)} / (1-AR)

  Furthermore, in the present embodiment, the first hematocrit sensor 5a and the second hematocrit sensor 5b as concentration measuring means are disposed on the blood circuit 1 side. Instead, the concentration measuring means is provided from the dialyzer 2. A blood index (hematocrit value, hemoglobin concentration, etc.) indicating the blood concentration may be measured from the dialysate pressure that is the pressure of the derived dialysate.

  Specifically, due to the difference between the venous pressure and the dialysate pressure, the pressure difference between the blood flow path in the dialyzer 2 and the dialysate flow path (intermembrane between the hollow fiber membranes (dialysis membrane) of the dialyzer 2). On the other hand, since the transmembrane pressure difference changes depending on the blood concentration of the patient circulating extracorporeally, the transmembrane pressure difference can be used as a blood index indicating the concentration of blood circulating extracorporeally. It is. In this case, it is not necessary to provide concentration measuring means on the blood circuit 1 side.

Next, a second embodiment of the present invention will be described.
As in the first embodiment, this blood purification device is for purifying a patient's blood while circulating it outside the body. The blood purification device is connected to a blood circuit 1 and a dialyzer 2 connected to a dialyzer 2 as blood purification means. It is mainly composed of a dialysis device body 6 that removes water while supplying it, and is applied to a dialysis device used in dialysis treatment. In addition, the same code | symbol is attached | subjected to the component similar to 1st Embodiment, and those detailed description is abbreviate | omitted.

  In addition, as shown in FIG. 8, the arterial blood circuit 1a and the venous blood circuit 1b in the present embodiment include the first solute in addition to the hematocrit sensors 5a and 5b for measuring the hematocrit value of the blood flowing through these blood circuits. A concentration measurement sensor 15a and a second solute concentration measurement sensor 15b are provided. The first solute concentration measurement sensor 15a and the second solute concentration measurement sensor 15b measure the solute concentration (urea concentration, etc.) of blood flowing through the arterial blood circuit 1a and the venous blood circuit 1b.

  Further, as shown in FIG. 9, the first solute concentration measuring sensor 15a and the second solute concentration measuring sensor 15b are electrically connected to the calculating means 11 ′, and the calculating means 11 ′ is connected to the true value deriving means 12. It is electrically connected to the clearance value calculating means 16 via '. Similar to the first embodiment, the calculation means 11 ′ constitutes a recirculation rate deriving means together with the water removal pump 8 that can give a specific peak, so that the recirculation rate (AR) is obtained. It has become. The method for deriving the recirculation rate (AR) is the same as in the previous embodiment.

  The recirculation rate obtained by the computing means 11 'is sent to a true value deriving means 12' constituted by a microcomputer or the like, for example, so that the true solute concentration (blood index) in the patient is obtained. Specifically, as shown in FIG. 8, the flow rate (shunt flow rate) of the shunt (such as a short-circuit portion of the blood vessel on the human body side) is Qa, and the flow rate of blood flowing through the blood circuit 1 by the action of the blood pump 3 (blood pump flow rate) ) Is Qb, the recirculated blood flow rate (recirculation flow rate) is Qr, the solute concentration measured by the first solute concentration measuring sensor 15a is Cin, and the solute concentration measured by the second solute concentration measuring sensor 15b is Cout. In addition, when the solute concentration (true solute concentration) of the shunt before the purification treatment is Ca, these are expressed by the following relational expression from the mass balance equation.

Cin × Qb = Ca × Qa + Cout × Qr (Formula 4)
(However, Qa ≦ Qb, Qb = Qa + Qr)

Here, since Qb = Qa + Qr, it can be expressed as Qa = Qb−Qr, and when the recirculation rate is AR, the recirculation rate (AR) = Qr / Qb, so that Qr = AR × Qb can be expressed, and when these are substituted into the above equation 4, the following equation is obtained.
Cin = Ca × (1−AR) + Cout × AR (Formula 5)

The formula for obtaining the true solute concentration Ca from the above formula 5 is as follows.
Ca = (Cin + Cout × AR) / (1-AR) (Formula 6)
That is, Cin, which is a measurement value of the first solute concentration sensor 15a, Cout, which is a measurement value of the second solute concentration sensor 15b, and AR obtained by the calculation means 11 ′ are known parameters. The true solute concentration Ca can be obtained.

  According to the present embodiment, as in the first embodiment, the true blood index in the patient is obtained by the true value deriving means 12 ′ based on the recirculation rate obtained by the computing means 11 ′ (recirculation rate deriving means). Since (solute concentration) can be obtained, ideal blood purification treatment can be performed in consideration of blood recirculation. Further, since the true blood index to be obtained by the true value deriving means 12 'is the solute concentration, the solute concentration and various indices obtained from the solute concentration can be obtained with high accuracy.

  Further, the true solute concentration obtained as described above is sent to a clearance value calculating means 16 constituted by, for example, a microcomputer or the like, and an index indicating the amount and efficiency of dialysis by the dialyzer 2 based on the true solute concentration. The clearance value K that is can be calculated. This clearance value K is a parameter mainly indicating the substance removal performance of the dialyzer 2 and represents how many mL of blood per minute that has passed through the dialyzer 2 has been purified.

Thus, the clearance value depends on the membrane area of the dialyzer used, the blood flow volume (blood volume circulating extracorporeally), the properties of the membrane, etc., and should be grasped in advance as a value (unique value) unique to the dialyzer. It is a parameter. When the clearance value K in the absence of water removal is generalized by a mathematical formula, it is as follows.
K = (Cin−Cout) / Cin × Qb (Expression 7)

  In the above formula 7, when there is no recirculated blood, Cin (solute concentration measured by the first solute concentration measuring sensor 15a) and Ca (true solute concentration) are equal, but when recirculated blood is generated. Since Cin and Ca are not equal, an error occurs in the clearance value grasped by the above general formula. Therefore, in this embodiment, based on the true solute concentration obtained by the true value deriving means 12 ′, the clearance value K0 (true value) is an index indicating the amount and efficiency of dialysis by the dialyzer 2 in the clearance value calculating means 167. The clearance value) is calculated.

When recirculated blood is generated, the solute (urea) removal amount (Ca × K) is obtained by the following equation.
Ca × K = Cin × (Ca / Cin) × K (Formula 8)
From the above equation 8, it can be considered that Ca / Cin is a correction coefficient for obtaining the true clearance value K0.

On the other hand, when Equation 5 is modified, the following relational expression is established.
Ca / Cin = {1- (Cout / Cin) × AR} / (1-AR) (Formula 9)
That is, since the correction coefficient for determining the true clearance value K0 can be obtained by the above equation 9, the true clearance value K0 can be obtained by multiplying the inherent clearance value K of the dialyzer 2 by the correction coefficient. it can. Therefore, the clearance value can be obtained with high accuracy in real time, and if used as an index during blood purification treatment, an ideal blood purification treatment can be performed in consideration of blood recirculation.

  However, in the present embodiment, as described above, the first solute concentration measuring sensor 15a and the second solute concentration measuring sensor 15b as concentration measuring means are disposed in the arterial blood circuit 1a and the venous blood circuit 1b, respectively. However, instead of this, it may be provided only in the arterial blood circuit 1b. In this case, if the water removal amount Quf (known parameter) by the water removal pump 8 is used, the true solute concentration Ca can be obtained as follows.

The following formula is obtained from the definition formula of the clearance value K.
K = {Cin × Qb−Cout × (Qb−Quf)} / Cin (Expression 10)
From the above equation 10, the above equation 6 becomes as follows, and the true solute concentration Ca can be obtained.
Ca = [{Qb−Quf} + (Qb−K) × AR / {1−AR × (Qb−Quf)}] × Cin (Formula 11)

  Although the present embodiment has been described above, the present invention is not limited to these embodiments. For example, the recirculation rate deriving means is in another form (for example, injecting physiological saline or the like into the venous blood circuit). And a recirculation rate may be derived by detecting the peak with an arterial blood circuit.

  In this embodiment, the true blood index to be obtained is a hematocrit value or a solute concentration. For example, a true blood index in another blood index (for example, hemoglobin concentration, protein concentration, etc.) is obtained. It may be a thing. The parameter calculated from the true blood index may be another parameter instead of the circulating blood volume change rate (ΔBV) or the clearance value as in the above embodiment.

  For example, PWI (plasma water index), which is an index of how much a change in body weight (decrease) due to water removal with respect to a patient affects blood concentration, can be calculated from a true blood index. This PWI is calculated by an arithmetic expression (PWI = ΔCPV% / ΔBW%) obtained by dividing the rate of change in circulating plasma volume (ΔCPV%) by the weight change rate of the patient (ΔBW%). As a result of the verification, it is clear that the numerical value is within an appropriate range when approximate to the weight.

  However, if PWI is large, it indicates that the blood concentration rate for weight loss due to water removal is large, and it is recognized that interstitial fluid is not replenished from outside the blood vessel even though water is taken away from the blood by water removal. On the other hand, if the PWI is small, it can be recognized that there is a margin for interstitial fluid replenishment even if water is taken from the blood.

Furthermore, an index of Kt / V can be used as another index indicating the dialysis efficiency to be calculated based on the true blood index (solute concentration). Such an index is obtained by the following equation. Here, K represents a clearance value, t represents time, and V represents a distribution volume.
Kt / V = ln (C (0) / C (t)) (Formula 12)
Substituting the solute concentration before the start of dialysis into C (0) and the true solute concentration obtained by the true value deriving means into C (t) in Equation 12 above, Kt / V considering blood recirculation is obtained. be able to.

  Furthermore, in this embodiment, the water removal pump is applied as a blood concentration means that gives a peak peculiar to a change in blood concentration by performing rapid and short-time water removal. Others may be used as long as they can concentrate blood. Still further, an alarm or the like may be sounded when the ratio of recirculated blood exceeds a predetermined value to alert the medical staff. In the present embodiment, the dialysis device body 6 is composed of a dialysis monitoring device that does not incorporate a dialysate supply mechanism, but may be applied to a personal dialysis device that incorporates a dialysate supply mechanism. .

  Based on the recirculation rate obtained by the recirculation rate deriving means, if the blood purification device has a true value deriving means for obtaining a true blood index in the patient, other treatments for purifying blood while circulating outside the body ( It can also be applied to those used in blood filtration therapy, hemofiltration dialysis therapy, plasma exchange therapy, etc., or those to which other functions are added.

1 is an overall schematic view showing a blood purification apparatus according to a first embodiment of the present invention. Schematic showing the dialysis machine body in the blood purification device It is a graph which shows control of the water removal pump in the blood purification apparatus, Comprising: The graph which shows performing water removal rapidly and in a short time The graph which shows the change of the hematocrit value detected with the 2nd hematocrit sensor in the blood purification apparatus The graph which shows the change (when there exists recirculation) of the hematocrit value detected with the 1st hematocrit sensor in the blood purification apparatus The block diagram which shows the connection relation of the 1st hematocrit sensor in the blood purification apparatus, the 2nd hematocrit sensor, a calculating means, a true value derivation means, a circulating blood volume change rate calculation means, and a display means. Explanatory drawing which shows typically the case where the recirculation blood has arisen in the blood purification apparatus Explanatory drawing which shows typically the case where the recirculation has arisen in the blood purification apparatus which concerns on the 2nd Embodiment of this invention. The block diagram which shows the connection relation of the 1st solute concentration measurement sensor in the blood purification apparatus, the 2nd solute concentration measurement sensor, a calculating means, a true value derivation means, and a clearance value calculation means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Blood circuit 1a ... Arterial side blood circuit 1b ... Vein side blood circuit 2 ... Dializer (blood purification means)
3 ... blood pump 4 ... drip chamber 5a ... first hematocrit sensor (concentration measuring means)
5b ... Second hematocrit sensor (concentration measuring means)
6 ... dialyzer body 7 ... dialysate supply device 8 ... water removal pump (recirculation rate deriving means)
DESCRIPTION OF SYMBOLS 9 ... Heater 10 ... Deaeration means 11, 11 '... Calculation means (Recirculation rate derivation means)
12, 12 '... True value deriving means 13 ... Circulating blood volume change rate calculating means 14 ... Display means 15a ... First solute concentration measuring sensor (concentration measuring means)
15b ... second solute concentration measuring sensor (concentration measuring means)
16: Clearance value calculation means

Claims (7)

A blood circuit comprising an arterial blood circuit and a venous blood circuit for extracorporeal circulation of collected patient blood;
A blood pump disposed in the arterial blood circuit;
Blood purification means connected between the arterial blood circuit and the venous blood circuit and purifying blood flowing through the blood circuit;
A concentration measuring means for measuring a blood index indicating the concentration of blood circulating extracorporeally in the blood circuit;
Recirculation capable of obtaining a recirculation rate that indicates a ratio of a flow rate of recirculated blood that is returned to the patient from the venous blood circuit to the arterial blood circuit and flows through the arterial blood circuit. Rate derivation means;
In the blood purification apparatus comprising
A blood purification apparatus comprising true value deriving means for obtaining a true blood index in a patient based on the recirculation rate obtained by the recirculation rate deriving means.   The concentration measuring means includes a hematocrit sensor that is disposed in the blood circuit and measures a hematocrit value of blood flowing through the blood circuit, and a true blood index to be obtained by the true value deriving means is a hematocrit value. The blood purification apparatus according to claim 1.   3. The blood purification apparatus according to claim 2, wherein a rate of change in circulating blood volume, which is an index indicating a patient's condition, is calculated based on a true hematocrit value obtained by the true value deriving means.   The blood purification apparatus according to any one of claims 1 to 3, wherein the concentration measuring means is disposed in each of an arterial blood circuit and a venous blood circuit in the blood circuit.   The blood purification means comprises a dialyzer for introducing or deriving dialysate through a dialysis membrane, and a blood index indicating the blood concentration from the dialysate pressure that is the pressure of the dialysate derived from the dialyzer by the concentration measuring means. The blood purification apparatus according to claim 1, wherein measurement is possible.   The concentration measuring means includes a hematocrit sensor that is disposed in the blood circuit and measures a hematocrit value of blood flowing through the blood circuit, and a solute concentration measurement sensor that measures a solute concentration of blood flowing through the blood circuit. The blood purification apparatus according to claim 1, wherein the true blood index to be obtained by the true value deriving means is a solute concentration.   The blood purification means comprises a dialyzer for introducing or deriving dialysate through a dialysis membrane, and an index indicating the amount and efficiency of dialysis by the dialyzer based on the true solute concentration obtained by the true value deriving means The blood purification apparatus according to claim 6, wherein a clearance value is calculated.

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